Remote sensing

GEOG 40323

March 20, 2018

Raster data: a brief review

  • Used to represent continuous phenomena
  • Each grid cell or pixel has a specific value

Types of raster data

Raster data resolution

  • Data with a smaller cell dimension have a higher resolution

Remote sensing and photogrammetry

  • Remote sensing: collection of aerial and satellite images for use within a GIS
  • Photogrammetry: the science of measuring geometry from images

Electromagnetic energy

  • Properties: wavelength, frequency, and amplitude

Source: National University of Singapore

Resolution in remote sensing

  • Relevant types:
  • Spatial resolution
  • Temporal resolution
  • Spectral resolution
  • Radiometric resolution

Data collection: satellites

Source: Digital Globe

Data collection: satellites

Source: Penn State

Types of satellites

  • Landsat
  • GeoEye/Digital Globe

Data collection: airplanes

Source: Penn State

Remotely sensed data models

  • Raster data (imagery)
  • Point cloud data (LIDAR)

Imagery in a GIS

Source: Esri

  • Data types: GeoTIFF, GeoJPEG, ECW, GRID, IMG, SID

Mosaicing

  • Process of combining multiple rasters into a single dataset

Source: Esri

Imagery operations

  • Georeferencing
  • Orthorectification
  • Spectral enhancement

Normalized Difference Vegetation Index

Source: Wikimedia Commons

Band manipulation

Source

Image classification

  • Types: supervised and unsupervised classification

Source: USDA

Change detection

Source: Earthzine.org

Feature extraction

Source: aeroterra.com

Urban applications of remote sensing